274 CHEMICAL AFFINITY. 



bined. These results certainly appear to prove that the 

 elementary particles of matter are not of the same 

 specific gravities. Do they not also indicate that any 

 alteration in the specific gravity of the atom would give 

 rise to a new series of compounds, thus apparently pro- 

 ducing a new. element? Surely there is nothing 

 irrational in the idea that the influences of heat or 

 electricity, or of other powers of which as yet we know 

 nothing, may be sufficient to effect such changes in the 

 atomic constituents of this earth. 



The combination of elementary atoms takes place 

 under the influence of an unknown force which we are 

 compelled to express by a figurative term, affinity. 

 In some cases it would appear that the disposition of 

 two bodies to unite, is determined by the electrical con- 

 dition ; but a closer examination of the question than 

 it is possible to enter into in this place, clearly shows 

 that some physical state, not electrical, influences com- 

 bining power. 



Chemical affinity or attraction is the peculiar dispo- 

 sition which one body has to unite with another. To 

 give some instances in illustration. Water and spirit 

 combine most readily : they have a strong affinity for 

 each other. Water and oil repel each other : they have 

 no affinity ; they will not enter into combination. If 

 carbonate of potash is added to the spirit and water in 

 sufficient quantity, the water is entirely separated, and 

 the pure spirit will float over the hydrated potash. If 

 potash is added to the oil and water, it combines with 

 the oil, and, forming soap, they all unite together ; but, 

 if we now add a little acid to the mixture, the potash 

 will quit the oil to combine with the acid, and the oil 

 will be repelled as before and float on the liquid. This 

 has been called single elective affinity. These elections 

 were regarded as constant, and chemists drew up tables 

 for the purpose of showing the order in which these 



